1. Field of the Invention
The invention relates to a device for measuring the distance between the device and a measuring surface, utilizing an interferometer.
2. Description of the Prior Art
The German Patent Application P 36 30 887 describes a device of the type under discussion. The interferometer used there supplies, at the output of the photoelectrical converter, not only an output signal corresponding to the interference between the light in the measuring and the reference wave guide, but, in addition, a direct current signal, since the photoelectrical converter is continually illuminated at any specific light level, and must have some positive voltage under those conditions. This direct current signal makes the further processing in, for example, a meter which is connected to the output side, more difficult. Filtering of the direct current signal by condensers is not possible. Since the disturbing direct current oscillates, compensation by means of a compensation voltage is not feasible.